We are studying regulation of sexuality in the male rat and are carrying out projects in the following areas: (1) Regulation of spermatogenesis, and influence of androgen binding protein, FSH, androgen concentrations in plasma, tubular cytosol and tubular nuclei on spermatogenic process in the intact and in the hypophysectomized rat, in which androgen filled implants have been placed. (2) Multi-annual rhythmicity of LH, testosterone and prolactin in the maturing male rat. (3) Effect of steroid replacement on the hormonal response to mating in the castrate male rat. (4) Effect of ablation of the medial preoptic area on the hormonal response to mating (or to the presence of the estrous female) and the ability of various compounds (steroids, releasing factors, catecholamines, amino acids) added intra-cranially to the ablated preoptic area to restore mating behavior. BIBLIOGRAPHIC REFERENCE: Kamel, F., W.W. Wright, E.J. Mock and A.I. Frankel, 1977. The influence of mating and related stimuli on plasma levels of LH, FSH, Prolactin and testosterone in the male rat. Endocrinology, in press.